1. Field
This invention relates to cam-action quick-release bicycle axle fasteners.
2. Prior Art
Cam-action quick-release axle fasteners for bicycles have been available for years, but existing designs have inherent disadvantages. They can be misadjusted or left disengaged by the user, causing a wheel to wobble or detach while riding. To overcome this, hub makers designed drop-outs with outer surfaces having depressions, holes, or tabs, which engage a complementary portion of the fastener. This retains the axle despite a loose fastener cam. However, these safety devices reduce the convenience of standard quick-release fasteners, since the user must both release the cam and loosen its adjustment nut to release the axle. The nut must then be readjusted each time the axle is attached to the drop-out. Many users are not mechanically competent to perform this adjustment, resulting in a fastener that is dangerously loose or tight.
Numerous other efforts have been made to improve the safety of quick-release axle fasteners. Some of these are now described and contrasted with the present invention.
The quick-release hub of U.S. Pat. No. 4,400,038 (Hosokawa) has a safety mechanism which prevents axle release until the cam lever is fully rotated. However, in the partly rotated position, it is susceptible to release from impacts.
The quick-release hub of U.S. Pat. No. 4,964,287 (Gaul) uses a cam with a removable lever or key for security. The key or lever can be lost. The cam position is hidden, so the user could assume the cam is engaged when it is not. Gaul has no safety interlock. His lock-down washers 26,28 do not serve this function, since they do not hold the axle in the drop-out when the cam is released.
The quick-release hub of U.S. Pat. No. 4,805,941 (Segawa, FIGS. 4,5) offers a safety interlock. His clamping mechanism needs enough range to fully relax the spring 6 of the interlock, since no radial lip is provided for its disengagement from the drop-out with the fingers. Thus, his interlock is inactive when it is needed most, in the loose position of the cam lever. When partially rotated, his cam lever is releasable by impact or vibration, defeating the safety.
The quick-release hub of U.S. Pat. No. 4,805,941 (Downing) has a safety hook for holding the axle in the drop-out. However, it requires a specialized drop-out for the hook assembly, it can be released by impacts, it is vulnerable to damage, and engagement of the hook is optional.